scholarly journals Influence of Nitrogen Rate, Seeding Rate, and Weed Removal Timing on Weed Interference in Barley and Effect of Nitrogen on Weed Response to Herbicides

Weed Science ◽  
2016 ◽  
Vol 65 (1) ◽  
pp. 189-201 ◽  
Author(s):  
Vipan Kumar ◽  
Prashant Jha
Keyword(s):  
Field Experiments ◽  
Plant Density ◽  
Agricultural Research ◽  
Integrated Weed Management ◽  
Barley Plant ◽  
Wild Oat ◽  
Seeding Rate ◽  
Weed Interference ◽  
Green Foxtail ◽  
Weed Removal

Field experiments were conducted at the Montana State University Southern Agricultural Research Center, Huntley, MT, in 2011 through 2013 to determine the effect of nitrogen (N) rate, seeding rate, and weed removal timing on weed interference in barley. A delay in weed removal timing from the 3- to 4-leaf (LF) stage to the 8- to 10-LF stage of barley resulted in up to 3.5-fold increase in total weed biomass and 10% reduction in barley biomass, and this was unaffected by a N rate that ranged from 56 (low) to 168 (high) kg ha−1. The effect of N rate on barley biomass was more pronounced when weed removal was delayed from the 3- to 4-LF stage to the 8- to 10-LF stage of barley and in nontreated plots. Increasing the barley seeding rate from 38 to 152 kg ha−1increased the barley plant density by 50%, biomass by 13%, and grain yield by 29%, averaged over N rates and weed removal timing. On the basis of 5 and 10% levels of acceptable yield loss, the addition of ≥112 kg N ha−1delayed the critical timing of weed removal by at least 1.3 wk in barley, compared with the 56 kg N ha−1rate. A medium or high N rate prevented reduction in barley grain quality (plumpness and test weight) observed when the seeding rate was increased from 38 to 76 or 152 kg ha−1at the low N rate. In a separate greenhouse study, the effect of N rate on the effectiveness of various herbicides for controlling wild oat, green foxtail, kochia, or Russian thistle was investigated. Results highlighted that wild oat or green foxtail grown under 56 kg N ha−1(low N) soil required 1.4 to 2.6 times higher doses of clodinafop, fenoxaprop, flucarbazone, glyphosate, glufosinate, pinoxaden, or tralkoxydim for 50% reduction in shoot dry weights (GR50) compared with plants grown under 168 kg N ha−1(high N). Similarly, a reduced efficacy of thifensulfuron methyl + tribenuron methyl, metsulfuron methyl, or bromoxynil+pyrasulfotole was observed (evident from the GR50values) for kochia or Russian thistle grown under low- vs. high-N soil. Information gained from this research will aid in developing cost-effective, integrated weed management (IWM) strategies in cereals and in educating growers on the importance of fertilizer N management as a component of IWM programs.

Economics of integrated weed management in herbicide-resistant canola

Weed Science ◽  
2006 ◽  
Vol 54 (1) ◽  
pp. 138-147 ◽  
Author(s):  
Bharat M. Upadhyay ◽  
Elwin G. Smith ◽  
G. W. Clayton ◽  
K. N. Harker ◽  
R. E. Blackshaw
Keyword(s):  
Weed Control ◽  
Weed Management ◽  
Field Experiments ◽  
Production Systems ◽  
Statistical Significance ◽  
Integrated Weed Management ◽  
Seeding Rate ◽  
Herbicide Resistant ◽  
Leaf Stage ◽  
Weed Removal

Integrated weed management (IWM) decision strategies in herbicide-resistant canola-production systems were assessed for net returns and relative risk. Data from two field experiments conducted during 1998 to 2000 at two locations in Alberta, Canada, were evaluated. A herbicide-based experiment included combinations of herbicide system (glufosinate-, glyphosate-, and imazethapyr-resistant canola varieties), herbicide rate (50 and 100% of recommended dose), and time of weed removal (two-, four-, and six-leaf stages of canola). A seed-based experiment included canola variety (hybrid and open-pollinated), seeding rate (100, 150, and 200 seeds m−2), and time of weed removal (two-, four-, and six-leaf stages of canola). For the herbicide-based experiment, strategies with glyphosate were profitable at Lacombe, but both imazethapyr and glyphosate strategies were profitable at Lethbridge. Weed control at the four-leaf stage was at least as profitable as the two-leaf stage at both sites. For the seed-based experiment, the hybrid was more profitable than the open-pollinated cultivar, seed rates of 100 and 150 seeds m−2were more profitable than 200 seeds m−2, and weed control at the two- and four-leaf stages was more profitable than at the six-leaf stage. When risk of returns and statistical significance was considered, several strategies were included in the risk-efficient set for risk-averse and risk-neutral attitudes at each location. However, the glyphosate-resistant cultivar, the 50% herbicide rate, and weed control at four-leaf stage were more frequent in the risk-efficient IWM strategy set. The open-pollinated cultivar, 200 seeds m−2rate, and weed control at the six-leaf stage were less frequent in the set. The risk-efficient sets of IWM strategies were consistent across a range of canola prices.

Competitive ability of hybrid and open-pollinated canola (Brassica napus) with wild oat (Avena fatua)

2002 ◽  
Vol 82 (2) ◽  
pp. 473-480 ◽  
Author(s):  
E. Zand ◽  
H. J. Beckie
Keyword(s):  
Brassica Napus ◽  
Weed Management ◽  
Plant Density ◽  
Management Program ◽  
Avena Fatua ◽  
Integrated Weed Management ◽  
Wild Oat ◽  
Replacement Series ◽  
Weed Interference ◽  
High Plant Density

The competitiveness of three hybrid and three open-pollinated canola cultivars against two wild oat populations was determined under controlled environment conditions at two plant densities and five canola:wild oat ratios (100:0, 75:25, 50:50, 25:75, 0:100). Analysis of replacement series and derivation of relative crowding coefficients (RCC), based on shoot dry weight or leaf area, indicated that hybrid canola cultivars were twice as competitive than open-pollinated cultivars when weed interference was relatively high (i.e., high plant density and vigorous wild oat growth). Little difference in competitiveness among cultivar types was apparent when weed interference was lower. The results of this study suggest that hybrid canola cultivars may be best suited for use in an integrated weed management program, particularly for farmers of organic or low input cropping systems. Key words: Hybrid canola, Brassica napus, Avena fatua, replacement series, competition

Variable crop plant establishment contributes to differences in competitiveness with wild oat among cereal varieties

2005 ◽  
Vol 85 (4) ◽  
pp. 771-776 ◽  
Author(s):  
John T. O’Donovan ◽  
Robert E. Blackshaw ◽  
K. Neil Harker ◽  
George W. Clayton ◽  
Ross McKenzie
Keyword(s):  
Spring Wheat ◽  
Field Experiments ◽  
Plant Density ◽  
Crop Plant ◽  
Wheat Crop ◽  
Wild Oat ◽  
Seeding Rate ◽  
Hordeum Vulgare L ◽  
Wheat Varieties ◽  
Crop Density

Field experiments were conducted at three locations in Alberta to determine the relative competitiveness with wild oat (Avena fatua L.) of three hard red spring (HRS) and three Canada prairie spring (CPS) wheat (Triticum aestivum L.) varieties and a semidwarf hull-less barley (Hordeum vulgare L.) (Falcon), and normal height general purpose barley (AC Lacombe). Crop variety significantly affected crop yield loss, wild oat shoot dry weight and wild oat seed yield (competitive indicators). AC Lacombe barley was consistently more competitive than Falcon barley or any of the wheat varieties, while the HRS wheat varieties were mainly more competitive than the CPS varieties. Falcon barley was generally similar in competitiveness to the CPS wheat varieties. Differences among varieties in crop plant density at establishment correlated significantly with the competitive indicators suggesting that this factor contributed to the differences in competitiveness among the varieties. Crop density tended to be higher with the more competitive AC Lacombe barley and HRS wheat varieties than with the less competitive Falcon barley and CPS wheat varieties. Variety and seeding rate did not interact significantly but intentionally increasing the seeding rate improved the competitiveness of all varieties. Key words: Hard red spring wheat, Canada prairie spring wheat, crop seeding rate, hull-less barley, semi-dwarf wheat and barley

Integrated Wild Oat (Avena fatua) Management Affects Spring Barley (Hordeum vulgare) Yield and Economics

1992 ◽  
Vol 6 (1) ◽  
pp. 129-135 ◽  
Author(s):  
David L. Barton ◽  
Donald C. Thill ◽  
Bahman Shafii
Keyword(s):  
Grain Yield ◽  
Field Experiments ◽  
Control Strategies ◽  
Integrated Control ◽  
Spring Barley ◽  
Barley Grain ◽  
Row Spacing ◽  
Wild Oat ◽  
Seeding Rate ◽  
Net Return

The effect of barley seeding rate and row spacing, and triallate, diclofop, and difenzoquat herbicide rate on barley grain yield and quality, and wild oat control were evaluated in field experiments near Bonners Ferry, Idaho, in 1989 and 1990. The purpose of the study was to develop integrated control strategies for wild oat in spring barley. Barley row spacing (9 and 18 cm) did not affect barley grain yield. Barley grain yield was greatest when barley was seeded at 134 or 201 kg ha–1compared to 67 kg ha–1. Wild oat control increased as wild oat herbicide rate increased and barley grain yield was greatest when wild oat herbicides were applied. However, barley grain yield was similar when wild oat biomass was reduced by either 65 or 85% by applications of half and full herbicide rates, respectively. Net return was greatest when the half rate of herbicide was applied to 100 wild oat plants per m2and was greatest when half or full herbicide rates were applied to 290 wild oat plants per m2. Net return increased when the seeding rate was increased to 134 or 201 kg ha–1when no herbicide was applied and when 290 wild oat plants per m2were present.

scholarly journals Control of a Sharpshooter with Exp 80698A and Karate, 1997

1998 ◽  
Vol 23 (1) ◽  
pp. 273-273
Author(s):  
M. O. Way ◽  
R. G. Wallace
Keyword(s):  
Relative Humidity ◽  
Plant Density ◽  
Agricultural Research ◽  
Experimental Unit ◽  
Seeding Rate ◽  
Plastic Cylinder ◽  
Spray Volume ◽  
Extension Center ◽  
Sweep Net

Abstract The experiment was conducted in a greenhouse at the TAMU Agricultural Research and Extension Center at Beaumont and was designed as a RCB with 6 treatments and 4 replications. The greenhouse was maintained at 31° C, 70% relative humidity, and 12 h light:12 h dark. Each experimental unit was a pot (6 inch diam X 6 inch deep) filled with sifted League soil. On 30 Sep, selected pots were planted with 8 untreated or EXP 80698A 75 FS-treated seeds. Seeds were treated at the rates shown in the table using the “Le Sak” method developed by Rhone-Poulenc Ag Company. On the same day, selected pots were sprayed with EXP 80698A 75 FS at the rates shown in the table using a 4 nozzle (800067 tip size, 50 mesh screens), hand-held spray rig pressurized with CO2. Final spray volume was 9.0 gpa. On the same day, pots were fertilized with urea at 51 lb nitrogen/acre. Immediately following planting, and spraying, soil in each pot was “raked” with forceps to simulate incorporation. On 5 Oct, rice emerged through soil. On 21 Oct, selected pots were treated with Karate at the rate shown in the table using the same spray rig and final spray volume as before. Immediately after spraying Karate, a plastic cylinder was placed over 2 plants in each pot. Cylinders were 3 inch in diam so that the plant density within a cylinder was equal to a seeding rate of 90 lb/acre, given 100% emergence and survival of seeds. The cylinders were ventilated with screen windows and tops. After securing the cylinders, which served as cages, each was infested on 21 (Oct 17 d after emergence of rice through soil) with 5 adult sharpshooters. Insects were collected from untreated rice using a sweep net. Two d later, cages were inspected for live and dead sharpshooters. Data were expressed as % mortality which was transformed using arcsine. Transformed data were then analyzed by 2-way ANOVA and means separated by DMRT.

Effects of Various Adjuvants on Sethoxydim Activity

1992 ◽  
Vol 6 (4) ◽  
pp. 865-870 ◽  
Author(s):  
K. Neil Harker
Keyword(s):  
No Value ◽  
Ammonium Sulphate ◽  
Field Experiments ◽  
Grass Species ◽  
Research Station ◽  
Wild Oat ◽  
Green Foxtail

Field experiments were conducted at the Lacombe Research Station from 1989 to 1991 to determine the influence of various adjuvants on sethoxydim activity. In all experiments sethoxydim was applied at 100 g ai ha-1to green foxtail, wheat, wild oat, and barley seeded in a canola crop. Of the four grass species, green foxtail was the most susceptible and barley was the least susceptible to sethoxydim. CC 16255 was the most effective adjuvant followed by either of two sources of ammonium sulphate (liquid or granular) and then Merge. Liquid and granular forms of ammonium sulphate were equally effective in enhancing sethoxydim activity. Several other adjuvants, including Enhance, Savol, and XE 1167, were moderately effective in the enhancement of sethoxydim activity. Adding Canplus 411 to Merge was not usually beneficial, but additions of Canplus 411 to Enhance often increased sethoxydim activity compared with sethoxydim and Enhance alone. Agral 90 and LI-700 were of little or no value as adjuvants with sethoxydim.

Seeding rate and row spacing affect flax yields and weed interference

1996 ◽  
Vol 76 (3) ◽  
pp. 537-544 ◽  
Author(s):  
F. C. Stevenson ◽  
A. T. Wright
Keyword(s):  
Seed Yield ◽  
Weed Management ◽  
Management Practices ◽  
The Other ◽  
Integrated Weed Management ◽  
Row Spacing ◽  
Flax Seed ◽  
Seeding Rate ◽  
Weed Interference ◽  
Interference Study

Seeding rate and row spacing are management practices that affect flax seed yield. Two experiments were conducted from 1988 to 1990 to determine the influence of flax seeding rates (300, 600, and 900 seeds m−2) and row spacings (9, 18, and 27 cm). One was a flax-weed interference study (three sites) and the other was a weed-free study (13 sites). In the presence of weeds, increasing seeding rate from 300 to 900 seeds m−2 improved flax seed yield by 180 kg ha−1, and reduced broadleaf weed yields by 300 kg ha−1 and grassy weed yields by 180 kg ha−1. In weed-free conditions, seed yield was not affected by seeding rate. Row spacing did not affect flax yield and had minor effects on weed yields when weeds were not controlled. When weeds were controlled, seed yield in the 9-cm row spacing was 9% (15% in the flax-weed interference study) greater than in the two wider row spacings. Seeding rate and row spacing independently influenced flax yield, and their effect was consistent among sites with weeds present, but was not consistent when weeds were controlled. Our results showed that flax seeding rate was an important component of integrated weed management. Key words: Flax, seeding rate, row spacing, weed interference

scholarly journals Response of Barley Genotypes to Weed Interference in Australia

Agronomy ◽  
2020 ◽  
Vol 10 (1) ◽  
pp. 99 ◽  
Author(s):  
Gulshan Mahajan ◽  
Lee Hickey ◽  
Bhagirath Singh Chauhan
Keyword(s):  
Negative Correlation ◽  
Weed Management ◽  
Field Experiments ◽  
Yield Loss ◽  
Production Systems ◽  
Relative Yield ◽  
Organic Production ◽  
Integrated Weed Management ◽  
Weed Interference ◽  
Barley Genotypes

Weed-competitive genotypes could be an important tool in integrated weed management (IWM) practices. However, weed competitiveness is often not considered a priority for breeding high-yielding cultivars. Weed-competitive ability is often evaluated based on weed-suppressive ability (WSA) and weed-tolerance ability (WTA) parameters; however, there is little information on these aspects for barley genotypes in Australia. In this study, the effects of weed interference on eight barley genotypes were assessed. Two years of field experiments were performed in a split-plot design with three replications. Yield loss due to weed interference ranged from 43% to 78%. The weed yield amongst genotypes varied from 0.5 to 1.7 Mg ha−1. Relative yield loss due to weed interference was negatively correlated with WTA and WSA. A negative correlation was also found between WSA and weed seed production (r = −0.72). Similarly, a negative correlation was found between WTA and barley yield in the weedy environment (r = −0.91). The results suggest that a high tillering ability and plant height are desirable attributes for weed competitiveness in the barley genotypes. These results also demonstrated that among the eight barley genotypes, Commander exhibited superior WSA and WTA parameters and therefore, could be used in both low- and high-production systems for weed management. Westminster had a superior WSA parameter. Therefore, it could be used for weed management in organic production systems. These results also implied that genotypic ranking on the basis of WSA and WTA could be used as an important tool in strengthening IWM programs for barley.

Time of Removal of Crownbeard (Verbesina encelioides) on Peanut Yield

2005 ◽  
Vol 19 (2) ◽  
pp. 380-384 ◽  
Author(s):  
Rodney L. Farris ◽  
Cody J. Gray ◽  
Don S. Murray ◽  
Laval M. Verhalen
Keyword(s):  
Natural Population ◽  
Field Experiments ◽  
Yield Reduction ◽  
Weed Density ◽  
Weed Interference ◽  
Weed Growth ◽  
Poor Predictor ◽  
Verbesina Encelioides ◽  
Shell Peanut ◽  
Weed Removal

Field experiments were conducted in southwestern Oklahoma near Colony in 2000 and near Ft. Cobb in 2001 to quantify the effect of time of removal of a natural population of crownbeard on peanut yield. Weed densities and dry weed weights were measured at eight weed-removal times, and in-shell peanut yields were determined at harvest. Crownbeard was removed at 0 (the weed-free check), 4, 6, 8, 10, 12, 14, and 16 wk (full season) after crop emergence (WAE). Weed density was a poor predictor for dry weed weight and peanut yield; however, dry weed weight and time of removal were good predictors for peanut yield. Weed growth was minimal up to 4 WAE and increased linearly after that time. For each week of weed growth, a 0.52 kg/plot increase in dry weed weight was measured. Peanut yield decreased linearly because of crownbeard competition. For each kilogram per plot increase in dry weed weight, a 129 kg/ha or 5.1% peanut yield reduction took place. For each week of weed interference, a 75 kg/ha or 2.8% peanut yield reduction occurred. Crownbeard removal by or before 4 WAE will minimize losses in peanut yield because of interference.

Effect of Application Factors on Efficacy of Fluazifop-P-Butyl in Flax

1991 ◽  
Vol 5 (3) ◽  
pp. 504-508 ◽  
Author(s):  
George H. Friesen ◽  
David A. Wall
Keyword(s):  
Growth Stage ◽  
Field Experiments ◽  
Time Of Day ◽  
Wild Oat ◽  
Spray Nozzle ◽  
Green Foxtail ◽  
Drought Conditions ◽  
Orientation Time ◽  
Moisture Conditions ◽  
Nozzle Orientation

Field experiments were conducted to determine the efficacy of fluazifop-P-butyl for the control of green foxtail, wild oat, barley, and wheat in flax as influenced by spray nozzle orientation, time of day, and growth stage. Under drought conditions in 1988, control of wild oat, wheat, and barley with fluazifop-P-butyl was enhanced 75%, 53% and 78%, respectively, when nozzles were oriented to spray forward 45°. Under adequate soil moisture conditions enhancement of control was minimal. Green foxtail control improved when fluazifop-P-butyl was applied from 1700 to 2100 h, but time of day had no effect on control of wild oat, barley, or wheat. Fluazifop-P-butyl effectiveness was reduced when applied 4 d after flax emergence due to late emerging grass seedlings. Green foxtail was the most tolerant to fluazifop-P-butyl, whereas wild oat, wheat, and barley were the most susceptible.

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